The invention generally relates to a connecting apparatus including a first component and a second component, as well as a connecting element. Preferably, the components include enclosure parts or shells of switching devices which are installed in a row or low-voltage switching devices, for example of circuit breakers.
Circuit breakers and other devices which are installed in a row, as well as their enclosure parts or halves, are normally connected via one or more poles by nuts and bolts, clips or brackets, or rivets. One enclosure shell and one cover shell typically have to be connected to one another for each pole. It is intended to be possible firstly to produce such connections cost-effectively and simply, such that they can be installed easily. Secondly, compression loads which occur as a consequence of arching influences are intended to be absorbed by the connections, and tolerances are intended to be compensated for, while allowing the enclosure shells to expand and ring when subjected to environmental conditions. A specific prestressing force is also intended to be exerted on the enclosure shells in order not only to ensure that the parts to be connected are protected against twisting, but also to ensure that the connection is protected against being inadvertently loosened.
While the use of a screw connection for connecting the components or enclosure shells to one another is, firstly, costly and, secondly, the screw connection must be secured against inadvertently becoming loose, for example by using varnish, a riveted joint offers only a small amount of compensation for tolerances in its longitudinal direction.
This is particularly true when the tolerances to be compensated for are additive. Furthermore, riveted joints easily bend when carrying out a riveting process using relatively long rivets. In addition, additional centering pieces have frequently been used in the past to protect the individual poles against twisting, even though this results in additional manufacturing and production costs.
At least two clips or brackets must be used, in a likewise costly manner, for a clip or bracket joint, which is likewise frequently used. In this case, the poles are firstly braced with respect to one another with only a small clamping force while, secondly, the clips or brackets can easily become loose, resulting in the risk of manipulation. A bonded joint, which has likewise been used in the past, does not allow the individual components to be dismantled without destroying them and, furthermore, does not ensure that the components are adequately braced with respect to one another.
A connecting element which is manufactured from a flat strip material is known from German Utility Model DE 83 22 594 A1, and this can also be used for circuit breakers having an elongated shaft, whose two shaft ends are T-shaped by means of integrally formed tabs. In order to insert the known connecting elements into the mutually aligned through-openings or holes in the components to be connected, one of the shaft ends is slotted such that the T-shaped holding or fixing tabs can be interlaced in the direction of the shaft longitudinal axis. This admittedly results in this shaft end being matched to the shaft width. However, this configuration necessarily leads to the cross section of the shaft, and hence the connecting element, being weakened, with the consequence that the cross section must be deliberately weakened over the entire shaft length by equidistant holes. Admittedly, it makes it possible to achieve a uniform material load and to avoid any weak point. However, this weakening of the cross section leads to a considerable reduction in the shaft cross section that can be loaded and hence to a reduction in the bracing force which is intended to be achieved by twisting the shaft, resulting in the length of the connecting element being reduced. Furthermore, during the twisting process, the entire slot, which is lengthened by means of an elongated hole, must be covered by a tool at the corresponding shaft end, and the opposite shaft end must be held in order firstly to secure this shaft end against rotation at the same time and, secondly, in order to achieve a tensile force, and hence a bracing force, which is as uniform as possible at the shaft ends. Furthermore, the complicated bending-in and bending-out mechanism with the slotted shaft end means that a number of twisting operations are required in order to ensure that the length of the connecting element is reduced sufficiently to brace the components.
The invention is thus based on an object of specifying a connecting apparatus of the type mentioned initially in which the disadvantages are avoided.
According to the invention, an object is achieved by the features of claim 1. To this end, a first mounting depression, which holds the holding end and is aligned with the through-openings, has a centering cone, the holding end-being conical, forming a mating surface which corresponds with the centering cone.
In consequence, the process of twisting the connecting element in order to brace the components firstly results in centering and secondly in a particularly short turning or twisting distance, without the material cross section being weakened along the shaft at the same time. Furthermore, in addition to reliable self-centering of the connecting element, which is preferably manufactured by stamping from a flat strip material, within the mutually aligned through-holes in the components, a tensile force which is uniform across the cross section of the connecting element is exerted on the opposite shaft end when a connecting element is twisted. In this case, this shaft end, which is also used as an insertion end, is inserted in a positively locking manner in a corresponding (second) mounting depression in the mounting state and before the connecting element is twisted.
In order to produce the positive lock for that shaft end which is opposite the conical holding end and is also used as the insertion end, it may be T-shaped with two fixing lugs. In this embodiment, diametrically opposite guide slots are provided in the through-openings in the components, in which guide slots the insertion end, and hence the two fixing lugs, are guided while the connecting element is being pushed through the through-openings.
In one particularly advantageous refinement, the connection in this variant is in the form of a bayonet fitting. To this end, when the connecting element is twisted, both fixing lugs are preferably guided at the insertion end along a respective ramp-like internal contour, which is provided in the (second) mounting depression, which holds the insertion end. In the process, the connecting element is preferably latched at the end of the twisting process and is thus fixed securely and detachably while exerting the desired bracing force. The ramp-like internal contour preferably has a number of recesses corresponding to the number of fixing lugs at the ramp end, into which recesses the fixing lugs are latched. In order to increase the bracing force further when the connecting element is in this fixing position, the shaft can also be twisted, so that its length is shortened. However, only a short torsional movement is then advantageously required for this purpose, with a half-twist or single twist. The ramp-like internal contour preferably extends over an angle of between 90xc2x0 and 180xc2x0 for each fixing lug, with the internal contour corresponding to a corresponding ramp circular segment.
In one alternative embodiment, the fixing lugs at the T-shaped insertion end are first of all bent inwards in the form of a circular arc, in an initial state, in order to match the external dimensions of the shaft. In the mounting state, that is to say once the connecting element has been inserted into the through-openings, the bent-in fixing lugs are bent radially outward. In order to allow the fixing lugs at the insertion end to be bent out outside the component or enclosure part facing them, in this case, the (first) mounting depression, which holds the opposite holding end of the connecting element, is designed to have two steps. The stepped internal contour is expediently formed by two notches, which run at an angle to one another, preferably at right angles, with different notch depths.
When the holding end of the connecting element is being fixed in position, the insertion end, which is provided with the fixing lugs, projects out of the mounting depression in a first comparatively deep position, and projects beyond the component or enclosure arrangement, so that the fixing lugs can be bent out radially in a simple manner. Following this bending process, the connecting element is pulled back and is fixed in a second position, which is displaced or offset axially outward with respect to the first position. In this case, the insertion end is at the same time pulled completely into this mounting depression that is associated with it.
The desired bracing force to brace the components or enclosure parts to one another is then produced by twisting the shaft of the connecting element. This is done by attaching an appropriate twisting tool to the insertion end, which is provided with the bent-out fixing lugs, with the centering effect on the holding end, which is opposite the insertion end, resulting in a more uniform tensile force being exerted on the connecting element. Furthermore, the comparatively large mating surfaces of the centering cone, which correspond with one another, on the one hand, and the centering cone at the holding end, on the other hand, advantageously result in the production of a friction force which is sufficient to avoid the holding end being rotated at the same time. There is thus no need to hold the connecting element firmly on both sides, at its two shaft ends. This embodiment is particularly suitable for connecting multipole circuit breakers having a corresponding number of enclosure and cover shells.
In another expedient refinement, the insertion end of the connecting element is designed like a fork, with two fixing lugs, which extend in the shaft longitudinal direction in an initial state, expediently being formed by an appropriate stamped-out area at the shaft end. The fixing lugs thus form a direct, straight-line extension of the shaft, without any projection at the sides. In the mounting state, these fixing lugs are bent out radially, and in this case the outward bend can be produced in the shaft plane, or transversely with respect to it.
In this embodiment, the connecting element is once again twisted by bending the fixing lugs out once the positive lock has been produced. In this case, the positive lock in the mounting state once again means that the number of turns that need to be made when twisting the shaft is particularly low, and, in particular, is just one turn.
The advantages achieved by the invention are, in particular, that the formation of a centering cone in a mounting depression which holds a conical holding end of a flat-strip-like connecting element firstly ensures centering and secondly ensures a high friction force, so that a high stress force is achieved, with simple handling at the same time, when the components provided with corresponding through-openings are braced. Furthermore, when the connecting element is being twisted in order to brace the components, a particularly short turning or twisting distance is achieved, with the connecting element being self-centered at the same time. Furthermore, in this case, only one connecting part is required, even for multipole devices, with a corresponding number of enclosure parts or shells for each such connecting point.
The connecting element provided for this purpose is, firstly, particularly simple and, secondly, is particularly robust since the material or shaft cross section is not weakened. The connection can also be made in situ in a particularly simple manner. When using galvanized steel strip or stainless material, this furthermore results in reliable corrosion protection. One major advantage is that it is possible to use already existing rivet holes or bolt holes in the enclosure parts. Since the positive lock, both at the holding end and at the insertion end of the shaft of the connecting element, is actually produced in the mounting state and before the turning and/or twisting of the connecting element, the reduction in the length of the connecting element required to apply the necessary bracing force, and hence the required torsional movement, are particularly short. In particular, they are considerably shorter than in the case of the cited prior art according to DE 83 22 594 U1.